1. Field of the Invention
The invention relates to a blind rivet nut setting device with a housing in which a tension bolt is arranged in a rotatable and axially movable manner, which projects out of the housing at least with a threaded region, and with a pneumatic/hydraulic pressure booster, which has a pneumatic cylinder and a hydraulic cylinder, wherein a pressure-controlled switch valve is provided, which in a first position connects the pneumatic cylinder to an outlet channel and in a second position connects the pneumatic cylinder to a pressure supply.
2. Discussion of Background Information
Blind rivet nuts are fastening elements that are to be arranged in an opening, for example, in a bore hole of a more or less thin-walled metal sheet. The blind rivet nuts thereby provide an internal thread and thus render possible a screw connection to metal sheets, the wall thickness of which is not sufficient to embody a thread. A blind rivet nut setting device is used to set the blind rivet nut. The blind rivet nut, which in the non-deformed state has a hollow cylindrical rivet shank at the one end of which a radially extending set head is embodied and on the other end of which an internal thread is formed, is thereby screwed onto the threaded region of the tension bolt with the set head first. The internal thread of the blind rivet nut and the external thread in the threaded region of the tension bolt must thereby correspond to one another.
Subsequently, the blind rivet nut is inserted with the rivet shank head first into the opening until the set head contacts. By start up of the blind rivet nut setting device, the tension bolt and thus the thread region are then moved axially backwards from the blind rivet nut and the sheet, whereby a compression of the rivet shank occurs. The blind rivet nut is then held captively in the opening.
To remove the blind rivet nut setting device from the set blind rivet nut, pressure on the tension bolt is relieved and it is rotated in the drill-off direction. The blind rivet nut setting device is then available for a new setting operation.
From DE 698 06 161 T2 a pneumatic/hydraulic rivet device is known, wherein a tension bolt with a threaded region is moved axially with the aid of a pneumatic/hydraulic pressure booster. The pneumatic/hydraulic pressure booster has a pressure supply, to which a system air pressure can be applied. Through the pneumatic/hydraulic pressure booster the system air pressure, boosted several times, is transferred to a hydraulic oil, which acts in the axial direction on the tension bolt. The setting operation is started by actuation of an actuating element. A valve is thereby opened, whereby a piston is displaced, so that the air supply necessary for the setting operation takes place to the pneumatic/hydraulic pressure booster. When a predetermined setting stroke has been carried out or a maximum setting force is achieved, air is released so that a new displacement of the piston takes place. The pneumatic/hydraulic pressure booster is separated from the pressure supply. The air contained in the pneumatic cylinder and compressed by the oil pressure is guided to a pneumatic motor such that it rotates the tension bolt in the drill-off direction.
With this solution, the complete setting operation runs automatically and cannot be interrupted. It is thereby necessary for the actuating element to be released again after a brief pressure, which is ensured by a complex construction of the actuating element. Since the control of the drill-off movement of the pneumatic motor takes place with the air contained in the pneumatic cylinder, a partial release of the air to relieve the pressure on the tension bolt is first necessary before the pneumatic motor can rotate the tension bolt. A relatively long pause is thus produced before the rotating-off with each setting operation, which is often felt to be disruptive.